Notice of incorrect soil CO2 concentration data (DP1.00095.001)

We have discovered that the atmospheric pressure correction for the soil CO2 concentration data product (DP1.00095.001) is not being performed, causing incorrect values to be reported.

This issue affects all TIS sites and, while the exact start date is not currently known with certainty, it started prior to 4 Jan 2019 and likely affects all previously published soil CO2 concentration data.

The magnitude of the impact is variable among sites (less pronounced for sites close to sea level and more substantial at high elevation sites), but also varies, albeit less markedly, with local conditions (e.g., temperature and CO2 concentration). As an example, omitting the pressure correction at atmospheric pressures of 100, 90, 80, and 70 kPa (roughly corresponding to elevations of 100, 1000, 1900, and 3000 m, respectively) resulted in an underestimate of true soil CO2 concentration by 2%, 15%, 28%, and 41%, respectively. These values were calculated assuming 10 °C temperature, 75% relative humidity, 20.95% oxygen concentration, and an uncorrected CO2 sensor reading of 1000 ppm.

Work has begun to correct this issue with the expectation of having it resolved by approximately July 2020. An update will be provided by the end of May 2020. Please use the data portal contact form for further inquiries; please select DP1.00095.001 in the Data Product dropdown list and include the term “PRB0040660“ in the body of your request.